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Magnavox 386SX-16 Upgrade options?

RWallmow

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I assume the first limit you would hit is the BIOS int13 one which means 8.5GB.

Its much more likely this PC has a 520mb limit, its only a 386, I know many 486's were limited by this one even. 8.5gb limit is more late 486/early pentium limitation.
Either one however can be overcome easily with a DDO like Ontrack, or find a way to install an additional BOOT-ROM in the system with the XT-IDE BIOS (boot ROM socket on Network Card is common).

If the OP goes SCSI, only REALLY early SCSI cards usually had limits like these, I have SCSI Macs, and PCs with cards dated 1989, that detect and boot 30+GB semi-modern SCSI drives just fine.
 

jh1523

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Well that may work for non-boot drives, but int13 is still used by scsi adapters for booting thus it should have the 8.5GB limitation (at least for the boot partition). Some cards do have an option "extended int13 translation" but it's card-specific and I'm not sure what the limitations of that would be.

That said, I have ran 6GB drives off the AHA1542CF without any problems.

Here's what Adaptec says about it:
http://ask.adaptec.com/app/answers/...port)-on-the-scsi-adapter-be-set-to-disabled?
http://ask.adaptec.com/app/answers/...s-on-the-adaptec-scsi-controller-be-disabled?
 

RWallmow

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Well that may work for non-boot drives, but int13 is still used by scsi adapters for booting thus it should have the 8.5GB limitation (at least for the boot partition). Some cards do have an option "extended int13 translation" but it's card-specific and I'm not sure what the limitations of that would be.

That said, I have ran 6GB drives off the AHA1542CF without any problems.

Here's what Adaptec says about it:
http://ask.adaptec.com/app/answers/...port)-on-the-scsi-adapter-be-set-to-disabled?
http://ask.adaptec.com/app/answers/...s-on-the-adaptec-scsi-controller-be-disabled?

That is true, but not likely to be an issue on a PC like this. Any version of MS-DOS/Windows someone would want to run on a 386-16Mhz, will only support 2gb partitions anyways.
Linux or 95/NT might cause issues with large boot partitions, but I cant think of any reason to run them on a box this slow, this is really suited to being a DOS/3.1 rig.
 

Stone

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I assume the first limit you would hit is the BIOS int13 one which means 8.5GB.
If you assume this you must also assume that he's using a FAT32 OS e.g., WIN95B or later. If not there will be a 2.15GB partition limit but you can have multiple 2.15GB partitions.
 

Stone

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That is true, but not likely to be an issue on a PC like this. Any version of MS-DOS/Windows someone would want to run on a 386-16Mhz, will only support 2gb partitions anyways.
DOS 7.xx makes a really fine OS and with 32-bit FAT support it also will support large HDs. I run this on my tweener.
 

PeterNC

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I wonder what one would do with gigabytes on a 80386. I think MBs is plenty for machines like this. IMO.
 

Chuck(G)

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Anent the 2GB partition limit in FAT16. I have an older camera that understands only FAT16 on CF cards. I routinely take 4GB CF and format them under XP as 4GB FAT16 and the camera does fine with them. Has anyone tried to install DOS/Win9x on a 4GB FAT16 partition?
 

krebizfan

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I would not use FAT-32 on drives attached to this system unless installed RAM was increased a lot. An 8GB drive formatted with FAT32 would need 8 MB to store the FAT. At up to 128kB each, there can be a lot of FAT16 partitions before system memory starts being a limiting factor.
 

jh1523

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If you assume this you must also assume that he's using a FAT32 OS e.g., WIN95B or later. If not there will be a 2.15GB partition limit but you can have multiple 2.15GB partitions.

Or perhaps he's not using DOS at all. I have Slackware installed on a similar machine, and the 2.1GB limit is irrelevant. :)
 

PeterNC

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Bought the 486 SX version today. This desktop was upgraded from a 486 SX to 486 DX 25. So that is pretty interesting. The MOBO appears identical to my 286 except for the CPU DB. I believe that they decided to use up inventory and built a 486 DB to sell the remaining inventory as 486. The MOBO is fine for 286/386SX with 1MB RAM standard, 256KB VGA standard and 3X ISA. But the Crystal is 16MHZ so it will be interesting to see how it performs once I receive it. Ironically the BIOS on this 486 is an older version than on the 386 displayed on this thread.

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PeterNC

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The MOBO has standard IDE. But if you want XMS you need >1MB RAM in case you use a HDD that is not a preconfigured type in the BIOS. I have a Quantum 105AT in my Magnavox 286 with 8MB RAM (maximum). Philips / Magnavox abandoned PCs > 386 so no 486 or higher CPU DABOs exist.

In the EU the Philips line was abandoned after 386 but in the US/CA they went through 486 as shown above.
 

vwestlife

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The keyboard port is on the side? Strange... and with the old motherboard design, you got all the expense of having a real Intel 486SX/DX chip (versus a cheapo Cyrix/TI 486SLC), but none of the actual performance benefit! :p

What is the "Music" chip on the motherboard?
 

Caluser2000

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Frow a dx2/50 in there and watch it fry cookie boy!! ;)

Pretty cool looking little beast though. Looking at the screen shot the cpu is running at 20Mhz max. That 16Mhz crystal is for the ISA expansion slots.
 
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PeterNC

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I am looking forward to receiving it. It will be an interesting experience.

The MUSIC chip is probably part of the I/O chips.

Thanks for the ISA bus 16MHZ crystal info. I did not realize that.

Other models:
Magnavox Maxstation 386 SX-20
Magnavox Magnum 386 SX-20
Magnavox Professional 386 SX-20
Magnavox Headstart SX-20
Magnavox Headstart 286
Magnavox Maxstation 286
Magnavox Magnum 286
Magnavox Professional 286
Magnavox Headstart SX
Magnavox Maxstation SX
Magnavox Magnum 386 SX-16
Magnavox Professional SX-16
Magnavox Professional 486SX
Magnavox Headstart 486SX
Magnavox Maxstation 486SX
Magnavox Professional 486/20 XP
Magnavox Headstart 486/20 XP
Magnavox Maxstation 486/20 XP
 
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Caluser2000

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Thanks for the ISA bus 16MHZ crystal info. I did not realize that.
You halve the rated crystal speed. If you go back and look at the OPs cpu board its got a 32Mhz crystal meaning, so halve that for the cpu clock speed. You might want to amend your vogons post.
 
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lee4hmz

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The keyboard port is on the side? Strange... and with the old motherboard design, you got all the expense of having a real Intel 486SX/DX chip (versus a cheapo Cyrix/TI 486SLC), but none of the actual performance benefit! :p

What is the "Music" chip on the motherboard?

That chip is just the VGA DAC; Music was a pretty well-known third-party DAC supplier back then.
 

Daniel Marsh

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I recently acquired a Magnavox Headstart SX on eBay in excellent shape. No visible discoloration on the case. Might as well have been NoS.

So far this is what I've done to it:
- I upgraded the ram to 8mb (have to disable the 1MB onboard via a toggle switch on a block of switches on the mainboard)
- Replaced the dead bios batteries with 2 new CR2430 cells
- Added a 2MB Cirus Logic ISA VGA card
- Added a i387 coprocessor (have to short a jumper on the daughtercard).
- Installed Dos 6.22 and WFW 3.11 on the 40MB HDD.

I would love to get a different processor daughtercard for this, but don't even know the part numbers to search. A 386sx CPU is a little anemic. I would love to get a DX33 if the system supports it.

I also saw this gentleman had added a very early external Magnavox CDD-461 CD-ROM drive. Be an awesome era-appropriate upgrade. Curious about the interface on it. Appears like it might be a 15 pin connector? Accessed through game port?

http://www.oldbrokenjunk.com/wordpress/?cat=32
 
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